Contents

Description

Kexecboot is a C program able to scan the partitions on available devices,
offering a graphical framebuffer menu and allowing user to select from which
one to boot. Specifically, kexecboot creates the command line for kexec.

Typically kexecboot resides together with kexec in a small initramfs,
embedded in a custom-tailored kernel compiled with support for initramfs and
kexec system call.
Both binaries are built static, linked against klibc to optimize size.

Flashed on NAND and launched as first kernel by the original bootloader,
this solution gives following advantages:

multi machine support: we build for many architectures using OpenEmbedded (tested on arm and x86/x86_64)

easy boot choice: boot from SD/CF/NAND/... even if bootloader doesn't support it

multiple fs detection: we support many filesystems e.g. ext2/3/4, jffs2, reiserfs, vfat and more (ubifs is work in progress)

kernel upgrade: no need to flash the device (kernel is in /boot of removable media)

rapid testing: different distributions can live in separate partitions on the same device

Thus, kexecboot is an interesting solution for embedded linux distributions,
which can just rely on kexecboot whithout having to consider what the real
bootloader can and cannot do.

About customization, initially the program has been developed for Sharp
Zaurus PDA (armv5te).
For the machines of that family there is specific code reading bootparams
directly from NAND, circumventing the obsolete bootloader which is
incompatible with modern 2.6.x kernels.

Proposed improvements

Write user's and developer's guides.

Extend architecture and filesystems support.

Improve debugging ability. We should allow users to have ability to look for debugging information without special hardware (serial cable e.g.).

Implement text-mode UI. We have already patches against one of old releases. This can be used later to use kexecboot UI over serial line or telnet/ssh connection.

Improve GUI. Make GUI more clean and eye-candy (fonts and icons).

Add ability to use multiple kernels on same partition. Current implementation allow to use only one kernel per partition.